The U.S. NTSB issued recommendations to the FAA to address a safety concern raised by two engine failures on Bombardier Canadair Regional Jet CRJ-200 aircraft. A flaw during the manufacturing process for fan blades led to the two engine failures, and the Board wants procedures set up to remove these blades before another incident occurs. A companion recommendation was sent to the Canadian government.
In both instances – a July 27, 2006 engine failure on an Air Nostrum CRJ shortly after takeoff from Barcelona, Spain, and a May 24, 2007 engine failure on an Atlantic Southeast airlines CRJ while in cruise flight from Syracuse to Atlanta – a fan blade on a General Electric CF34-3B1 turbofan engine fractured, causing a loud bang, severe vibration and in one case an engine fire. Both flight crews declared emergencies and landed safely with no injuries.
Examination of the blades showed that they failed due to a material defect introduced during the manufacturing process. The Board issued six recommendations to the FAA, including that it require GE Aviation to define a reasonable maximum time frame below 4,717 cycles since new for these Teleflex fan blades and require that the blades be removed from service before that limit is exceeded, to require GE to include additional testing in the manufacturing process for those blades, and to require GE to make modifications in its CF34-1/-3 engine design to ensure that high engine vibrations (such as can happen when a fan blade fractures) will not cause the engine to catch fire.
The Board also issued a recommendation to Transport Canada to require Bombardier to redesign the retention feature of the CRJ 100/-200 engine throttle gearbox to ensure that it can withstand the loads generated by a fan blade separation or similar event. (NTSB)